Susan Wicks is a poet whose capacity to transfigure everyday objects into universal emblems of love and loss has gained her popularity as well as succes d'estime. Driving My Father, the touching memoir she brought out last year, showed that her mastery of the expressive domestic detail could be as effective in prose as it is in verse. Wicks's readers have been impressed by the delicacy and focus of her language, but they've also have been won over by her honesty and emotional generosity.

It comes as quite a surprise, then, to discover what a sad, screwed up, immature - and even bitchy - heroine she's chosen for her first novel,The Key. Narrated in the first person, it explores the damaged psyche of Jan Hickman, a middle-aged, middle-class divorcee whose children have recently left home. Jan runs a bookshop in a small provincial town, and her humdrum life is punctuated by nothing more exciting than going to aerobics classes and giggling over the personal ads in the local paper. Flashbacks reveal that in her twenties she had an adulterous affair with her psychology tutor on an adult education programme. The man turned out to be a disaster - patronising, inadequate, an emotional sadist addicted to humiliating women.

Fifteen years on, Jan is still damaged and embittered by the experience. She decides to turn the tables on the male sex by transforming herself into a heartless seductress. She selects a victim as vulnerable as she herself was all those years ago - a nerdy, thirtyish architect who's recently lost his job and lives with his parents - and calculatedly sets about making him fall in love with her.

This brief summary makes the narrative seem more focused and dramatic than it really is. In fact, Jan's developing relationship with the young man is interwoven with a series of additional strands which makes the novel feel rather diffuse despite its brevity: memories of the old affair, thoughts about her two daughters, scenes in the bookshop, conversations with her friend Deborah, descriptions of her cottage, French madrigals, and moments of horrifying loneliness.

This is a book in which character and language are far more important than plot. The storyline could have been tighter and better directed, but Jan's personality is just about complex enough to maintain the narrative momentum on its own. She has too much psychological depth to be labelled merely a villain or a victim. We are never asked to pass moral judgement upon her, but nor do we ever fell comfortable enough with her to identify wholly with her viewpoint. If not quite an "unreliable narrator", she is certainly a tricky one: she doesn't lie to us, but then she doesn't tell us everything she needs to know.

The result is an intriguing but uncomfortable read - beautifully written, and full of the kind of detailed observations you'd expect from Wicks - but somehow difficult to get to grips with.